X-ray backscatter imaging is getting more and more important in security inspection because it can well detect the material of an object with a low atomic number. An embodiment is as follows: a flywheel rotates about a radiation source to form a pencil beam, and the pencil beam interacts with an inspected object to form a flying spot through Compton scattering. A back-scatter detector collects X-ray backscatter rays of the flying spot at any time, and after processing, information of the material is obtained, i.e., a backscatter image is formed. After continuous scanning, internal information of the whole object inspected can be processed and obtained, and objects with a lower atomic number, e.g., contraband goods such as explosives, drugs, hidden in concealed locations such as vehicle door interlayer, vehicle bottom, could be highlighted.
The existing flying point device operates as follows: a radiation source generates fan-shaped X-rays that pass through a rotating shield with multiple collimating holes to continuously generate a pencil beam for achieving a first dimensional scanning, and achieving a second-dimensional scanning by rotating or translating the rays to scan sectors.
However, if objects with different sizes are lined up, and the existing backscatter device is stationary in its scanning angle and scanning position including vertical and horizontal position, the view angle of the image is possibly bad, such that occlusion or overlap is formed between internal structures of the inspected objects, and suspicious goods cannot be highly identified under this angle.